Many packaging containers for liquid food are manufactured in so-called portion volumes, intended to be consumed direct from the package. The majority of these packages are provided with drinking straws in a protective envelope which is secured to the one side wall of the packaging container. The packaging containers, which are often parallelepipedic in shape, are manufactured from a laminate with a core of paper or paperboard, with layers of thermoplastics and possibly aluminum foil. On the one wall of the packaging container—most often the top wall—a hole has been punched out in the core layer and this hole is covered by the other layers of the laminate, which makes it possible to penetrate the hole with the drinking straw which accompanies the packaging container, and hereby consume the drink enclosed in the package.
There have long been machines which apply drinking straws in their protective envelopes to packaging containers which are conveyed through the machine. Such a machine, i.e. a drinking straw applicator, is, for example, described in the European Patent Specification EP-1,042,172. The applicator functions in that a belt of continuous drinking straw envelopes with drinking straws is guided in towards and surrounds a drive means. Adjacent the drive means, there are devices for severing the drinking straw belt into individual drinking straws enclosed in a protective envelope, as well as devices for applying the drinking straw to one side wall of the packaging container, the packaging container being advanced on a conveyor through the machine. Prior to the moment of application, the envelope drinking straw is provided with securement points. The securement points may, for example, consist of hot melt, which is molten glue which glues the drinking straw envelope in place and retains it when the glue has hardened.
Today straw applicators may operate in ultra high speeds, handling approximately 40,000-50,000 packages/hour. The Swedish patent application No. 1451136-4 describes an ultra high speed straw applicator.
One issue with straw applicators, irrespective of operational speeds, is the difficulty of retaining the drinking straw on the wall of the packaging container at exactly the same position, with an application device, while at the same time conveying the packaging container through the straw applicator. If the application device and the conveyor, on which the packaging container is transported, become un-synchronised, even just slightly, the drinking straw will lose its position on the packaging wall and the glue will smear. In most cases the end result will only be a less attractive packaging container, but in a worst case the bonding strength between the drinking straw and the packaging container is considerably reduced, with an increased risk that the drinking straw will detach from the packaging container during handling. The Swedish patent application No. 1451542-3 describes a solution in which the drinking straw is not moved, relative the packaging container, in the direction of the conveying direction, i.e. in the direction in which the packaging container is moved during application. The movement of the application device is compensated such that the application device will, during the application, follow the drinking straw in the lengthwise straw direction.
Another issue that may still exist is that the drinking straw is undesirably moved, relative to the packaging container, in the lengthwise direction of the drinking straw. Such movement may cause smear of the glue and there will be a risk that the drinking straw is not properly attached to the packaging container. The movement is caused by friction between the envelope of the drinking straw and the contact surface of application device.